of some New Species of Hymenopterous Insects. 395 
regulate the formation of genera. The insect, for the reception of 
which I have established the present genus, is perhaps strictly 
a species of Megachile, since in that genus we find an infinite 
variety in the form of some organs in the male sex of different 
species ; we have one species found in this country, Megachile 
Willughbiella, of which Mr. Kirby observes, “ This sex (male) of 
our insect exhibits a peculiarity which none of those that are 
related to it in the form of the anterior tarsus possess ; the last 
joint of its antenne is larger than any of the rest, which gives 
them some resemblance to those of a Papilio.” The antennze 
thus described are, however, exactly like those of the majority 
of the males of Megachile, with the exception of the apical joint, 
which is compressed, and, when viewed laterally, presents the 
club-shaped form alluded to. In the insect here described the 
antennee are extremely slender and elongate, as in the genus 
Eucera, with the two apical joints forming a knob, or club, as in 
the beautiful Lepidopterous genus Argynnis. 
Thaumatosoma Duboulau. (Pl. XXI. fig. 1.) 
Male.—Length 5 lines. 
Black, the head and thorax opake, very finely and closely 
punctured; the face with a thin clothing of long silvery pu- 
bescence, that on the clypeus is more dense, shorter, and has a yel- 
lowish tinge ; the antenne ferruginous, with the apical knob or 
club black. The sides of the thorax with a thin cinereous pubes- 
cence ; the wings subhyaline, their nervures black; the tegule 
rufo-testaceous behind. Abdoinen shining and closely punctured ; 
the posterior margins of the segments with a narrow fringe of white 
pubescence ; the fourth segment clothed with fulvous; the fifth 
and sixth finely rugose, the latter slightly but widely emarginate ; 
the seventh segment concealed beneath the sixth, its margin 
armed on each side with a short acute tooth, and also having two 
longer blunt marginal spines which are equidistant from each 
other and from the lateral spines; the basal segment produced 
beneath into a blunt projecting node. 
The specimen described is in bad condition; judging from the 
ragged state of the wings, and the rubbed thorax and abdomen, it 
must have been long disclosed at the time of capture ; the white 
abdominal bands are nearly obliterated. I have named it, as a 
mark of compliment and encouragement to its captor, F, Du 
Boulay, Esq. 
Hab. West Australia. 
